Many rotary seal designs are well known in the art and are commercially available for sealing a space between two parts. So-called mechanical seals of this nature include members fastened to the two parts and a sliding connection between the two members. Such seals are effective but also relatively expensive and large. Lip seals are less expensive and smaller, and usually include a seal member that is fastened to one of the two parts, the member having a flexible lip that slidingly engages the other part.
U.S. Pat. No. 3,601,412 shows lip seals of this nature. In U.S. Pat. No. 3,601,412, an elastic seal member is fastened to a rotatable shaft and a flexible lip of the member slides against a frame part. It is necessary to hold the lip against the frame part, and this patent shows special supports for this purpose. In an instance where a two-sided seal is needed, FIG. 6 of this patent shows lip seals and supports on opposite sides of the frame part. Such an arrangement is not compact and it is relatively expensive because of the need for the supports that hold the lips against the frame part.
U.S. Pat. No. 3,810,636 shows a bearing seal extending between the races of a roller bearing, the seal including flanges which are located on opposite sides of ribs formed on the races. A problem with this arrangement is that it does not include an inherent preload between the flanges and the ribs, which generally is necessary to ensure a seal during rotary operation and during periods of inactivity.
It is a general object of this invention to provide an improved double-acting lip seal which is compact, relatively inexpensive, and includes an effective preload on the lips.